Door and panel construction



Mal C11 4, M PASQUIER DOOR AND PANEL CONSTRUCTION Filed Sept. 19, 1938 Patented Mar. 4, 1941 PATENT OFFICE DOOR'AND PANEL CONSTRUCTION Michel Pasquier, Portland, reg., assignor to M and M Wood Working Company, Portland, 0reg., a corporation of Oregon Application September 19, 1938, Serial No. 230,557

Claims.

door and panel construction wherein a frame is overlaid on both sides thereof with plywood panels consisting of a plurality of plies of wood 5 veneer, and has particular reference to a construction which will counteract the stresses created by expansion or contraction of the wood veneers which causes the door to warp or twist out of a fiat plane.

A type of door and panel construction in use at the present time is that which employs a frame consisting of stiles and rails and having a core member or filler consisting of spaced bars or cross members. Glued to each side of the frame is a sheet of plywood comprising a plurality of plies of wood veneer, the whole being overlaid with a ply of veneer of the wood required for the desired finish. Such construction embodies the quality of being highly resistant to thermal conductivity, as well as being strong and durable and possessing a massive appearance. Hollow panel doors of this character are economical to manufacture, and their lightness results in substantial economies in transportation and handling charges. I

A problem confronting manufacturers of this type of door is the tendency of such doors to warp or bend out of a flat plane. The absorption of moisture by the wood veneers causes the wood to expand, and consequent distortion of the door is a very positive result; Not until applicants discovery of the present invention has any means been known which will counteractthe unequal stresses created upon opposite sides 85 of the panel by expansion or contraction of the wood. Applicant has discovered that by interposing a sheet of metal between plies of the wood veneer which compose the plywood faces of the panel, and so arranging the metal sheets in the opposite plywood faces as to provide a balanced construction, the door or panel so constructed will not warp or bend out of a flat plane. Additional advantages of this type of construction are that a panel so constructed is highly fire re-' sistant, and that its strength is greatly increased.

Primarily, the object of the invention is to provide a construction for a door and the like which will effectively counteract the stresses normally created by expansion or contraction of the wood.

It is a further object of the invention to provide a door and the like which is unaffected by absorption of moisture by any of its component parts.

This invention relates to improvements in A further object of the invention is to provide a construction for doors and the like comprising a frame overlaid with veneers and having metal sheets interposed between veneers on opposite sides of the frame, resulting in a panel 5 which will not warp or bend out of a fiat plane, which is strong and durable in construction, light in weight, and practical and economical to manufacture.

the construction.

Figure 2 is a fragmentary sectional elevation of the panel, taken on the line 2-2 of Figure 1.

Figure 3 is a perspective view of a fragmentary portion of a panel illustrating a modified 25 form of construction embodying the invention. Preliminary to a more detailed description-of the invention, attention is directed to the wellknown fact that upon the absorption of moisture, wood expands in a direction normal to its 30 I grain, rather than in a direction. parallel with the grain. The application of heat does not cause wood to expand, but rather serves to evaporate the moisture therefrom, causing the wood to contract. In other words, the expansion or35 contraction of wood is directly attributable to its moisture content, rather than to changes in temperature. 0n the other hand, metal is not affected by changes in humidity, and the moisture content of wood veneers bonded to metal sheets, as herein described, has no appreciable eflect thereupon.

In the present invention, wherein the construction is composed in part of plywood, a sheet of metal is interposed between two sheets of 45 wood veneer and the veneers firmly bonded thereto by a highly water resistant bond. The grain of each sheet of wood veneer bonded to the metal is normal to the grain of the wood of the other sheet of veneer bonded thereto. In other 50 words, the grain of the veneer bonded to one side of the sheet of metal runs in a direction at a right angle to the direction of the grain of the veneer bonded to the other side of the sheet of metal. Therefore, because of the stability of 55 mean temperatures, the wood veneers bonded thereto iare. held immovable relative to the metal,

and-in'a balanced construction no warping or bending takes place.

While the construction herein described is adequate to counteract the expansion and contraction of the component parts, deformation or distortion of thepanel may occur unless the construction is so balanced that the tension exerted by the metal sheets is distributed equally to both surfaces of the panel. For this reason, whether the opposite faces of the panel be separated by a frame, as in the construction illustrated in Figures 1 and 2 of the drawing, or separated by the interposition of additional plies of wood veneer, as illustrated in Figure 3, it is imperative that the stresses exerted on one side of the center plane of the panel are opposed by equal stresses exerted on the other side of the panel. The reason for this will be better understood if it be remembered that no two pieces of wood have an identical cellular formation in every part, and do not take up moisture in equal quantitles. The structure and texture of the grain in any one piece of wood is unlike that in any other piece of wood, and, in a structure such as herein described, the moisture content and consequent expansion or contraction of wood veneers on opposite sides of the frame is variable.

The interposition of a sheet of metal between transverse plies of wood veneer, the metal being stronger than the wood, serves to equalize the variabilities of the wood and exerts a like amount of tension on both sides of the center plane of the panel.

Referring to the drawing, Figures 1 and 2 illustrate a door or panel comprising a frame made up of stiles l and rails 2 and having disposed therewithin a hollow core member or filler consisting of cross members 3 disposed in spaced relation to each other and to the rails 2. Each side of the frame is covered with a plurality of wood veneers which are bonded to each other and to the frame and core member by means of a water resistant glue. The wood veneers comprise a sheet of plywood, generally indicated at 5, which is so constructed that the grain of alternate plies of wood veneer is normal to the grain of the adjacent plies, thus providing a construction wherein the grains of veneers bonded together in face to face relation are disposed transversely one to the other.

Interposed between two plies of wood veneer is a sheet of metal 6 to which both piles of veneer are bonded in the same manner as the plies of veneer are bonded to each other. It is preferable for reasons which are believedto be obvious, that the sheet of metal be positioned at as great a distance from the center plane of the panel as possible without sacrificing the peculiar advantages incident arranging the metal between transverse plies of wood veneer. The axial plane or center of the panel is the fulcrum about which the wood veneers must bend to cause the panel to warp or bend out of a flat plane. That which causes the panel to warp or bend is the tension created upon one side of the panel by the unequal moisture content of the opposed faces of the panel. For all intents and purposes, all of the material between the metal sheets in applicant's construction is a part of the frame or core member, and, because of theimpermeable character of the metal, is not subject to change in moisture content. It is the variability of the moisture content of the wood veneers outwardly of the metal sheets, therefore, which must be taken into consideration, and to counteract unequal stresses imposed by expansion or contraction of these wood veneers and thus hold the panel in a flat plane, each of the metal sheets must have a greater tensile strength than the wood veneers bonded to the outer face thereof.

Veneers which compose the plywood faces of panels such as herein described are commonly made in thicknesses from one-sixteenth to oneeighth inch; and in a construction in which the metal sheets are interposed between the two outermost plies of veneer, sheets made of 38 gauge metal are adequate for counteracting the unequal stresses imposed upon the panel by the variable moisture content of the outermost veneers and for holding the panel in a flat plane.

In Figure 3 is illustrated a modified form of construction embodying the invention in which the panel is made up of a plurality of plies of wood veneers 8, said veneers being so arranged that the grain of alternate plies is normal to the grain of adjacent plies, as heretofore described. Between the two outermost piles on each side of the panel is interposed a sheet of metal 9, the sheet of metal being thus interposed between transverse grains of wood veneer. *In the construction illustrated, the core member of the panel is composed of additional sheets of wood veneer interposed between those bonded to the metal sheets, theonly material difference in construction from that illustrated in Figures 1 and 2 being that the panel is not hollow.

Having now described my invention and in what manner the same may be used, what I claim as new and desire to protect by Letters Patent is:

l. A construction for doors and panels and the like having a frame overlaid on both sides thereof with plywood consisting of a plurality of plies of wood veneers, the grains of successive plies of wood veneer being normal to each other, and a sheet of metal interposed between and bonded to transverse plies of wood veneerson each side of said frame for counteracting unequal stresses imposed thereupon by the expansion or contraction of said wood veneers, the grain of each ply of veneer bonded to the metal being normal to the grain of the other ply of veneer bonded thereto.

2. A construction. for doors and panels and the like having a frame overlaid on both sidespthereof with plywood consisting of a plurality of piles of wood veneers, and a sheet of metal interposed between and bondedto transverse plies of wood veneers on each side of said frame and in spaced relation to the center plane thereof for counteracting unequal stresses imposed upon said frame by the expansion or contraction of said wood veneers, the grain of each ply of veneer bonded to the metal being normal to the grain of the other ply of veneer bonded thereto.

3. A construction for doors and panels and the like having a frame overlaid on both sides thereof with plywood consisting of a plurality of piles of wood veneers, and a sheet of metal interposed between and bonded to transverse piles of wood veneers on each side of said frame for counteracting unequal stresses imposed upon said frame by the variable moisture content of said wood veneers, the grain of each ply of veneer bonded to the metal being normal to the grain of the other ply of veneer bonded thereto, the tensile strength of each of said metal sheets being greater than the tensile strength of wood veneers bonded to the outer face thereon 4. A construction for doors and panels and the like having a frame overlaid on both sides thereof with plywood consisting of a plurality of piles of wood veneers, the grains of successive plies of wood veneer being normal to each other, and a sheet of metal interposed between and bonded to transverse plies of wood veneers on each side of said frame in spaced relation to and parallel with the plane of the center of said frame for counteracting unequal stresses imposed upon said frame by the variable moisture content of said wood veneers, the grain of each ply of veneer bonded to the metal being normal to the grain of the other ply of veneer bonded thereto, the tensile strength of each of said metal sheets being greater than the tensile strength of the wood veneers bonded thereto.

5. A non-warping construction for doors, panels and the like, comprising a frame member consisting of stiles and rails and defining a substantially hollow core, said hollow core being closed by panels of plywood overlaid on both sides of said frame, said panels consisting of a plurality of plies of wood veneer having the grains 'of successive plies normal to each other, and a sheet of metal bonded between transverse plies of said veneer on both sides of said frame for resisting unequal stresses in said wood veneers on opposite sides of said frame.

- MICHEL PASQUIER. 

